Introduction On 29 May, 2004, a system of severe thunderstorms in northeast Colorado produced an...
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Transcript of Introduction On 29 May, 2004, a system of severe thunderstorms in northeast Colorado produced an...
IntroductionOn 29 May, 2004, a system of severe thunderstorms in
northeast Colorado produced an outflow boundary of cold air.
This outflow and resulting temperature gradient contributed to
winds with gusts as high as 40 m/s (90 mi/h). The storm
tracked towards the east-southeast, over land that had been
experiencing an extended drought. The wind, in conjunction
with the land condition, initiated a wind erosion event that
carried soil dust for at least 355 km (220 miles) past Hays,
Kansas. The dust storm caused severe damage to the land
and dramatically lowered visibility. Many traffic accidents and
even two deaths were attributed to the storm. This study helps
to better understand the genesis and progression of such
storms and to evaluate the ability of the USDA-ARS Wind
Erosion Prediction System (WEPS) model to simulate such
events.
J. Tatarko, USDA-ARS; M. Knapp, Kansas State University;S. van Donk, and E.L. Skidmore, USDA-ARS; Manhattan, Kansas
Deadly Dust: A case study of a Great Plain dust storm
USDA-ARS-WERU1515 College Ave.Manhattan, KS 66502
For more information about WEPS, please contact :
Email: [email protected]; Phone: 758-537-5559
WEPS SimulationsWeather and field data provide a unique opportunity to assess the ability of the
WEPS model to simulate such wind erosion events. For the period 1999-2004,
we obtained detailed historical weather records, soil data for the dominant soils,
average yields, and typical crop rotations for Goodland, Kansas. These data
were used in WEPS and simulations made for 6 year rotations and the event
(5/29/04) using measured and simulated weather (see table below).
Storm observations indicate that while the soil eroded on many fields, on others
it did not (see aerial photos). Interviews with the Goodland DC indicate that crop
rotations on fields that eroded included grain sorghum, corn, and some winter
wheat where the previous drought afforded little residue and poor crop stands in
the spring of 2004. While WEPS did show soil loss likely for the rotations using
simulated weather, losses were much greater using the much drier measured
weather on irrigated crops and still higher for dryland situations. Corners of
some irrigated fields blew (see aerial photos, left) and are considered as dryland
scenarios in the simulations. The Goodland DC indicated that some wheat land
was blowing on 29 May, but WEPS does not show loss for that day for wheat.
However, others interviewed indicated that most wheat land did not erode on 29
May because of sufficient cover but that such land did have erosion events in
April because of poor cover. WEPS did predict erosion on 16&17 April of 2.6 and
7.7 kg/m2 respectively. Dryland grain sorghum and corn did show significant soil
loss for 29 May as was observed in the field by the DC.
11:45 MDT – SE of Akron, ColoradoA severe thunderstorm system, southeast of Akron, Colorado,
causes a downburst. A downburst is the result of hail or large
raindrops falling through dry air. The hailstones melt or
raindrops evaporate – the evaporation demands a lot of energy
so the air is cooled. The higher density cold air falls as a "cold
air balloon". As the cold air balloon falls, a strong downdraft
induces an outburst of damaging winds on or near the ground.
~15:45 MDT – Bird City, Kansas“My anemometer is located only 9 feet off the ground and between
windbreaks and registered in the 50-60 mph range but neighbors
clocked 80-90 mph straight lined winds. It was an unbelievable
storm. It reminded me of some hurricane videos I've seen. The
roar grew until our house shook. The south side of the barn was
blown off its foundation.” - John Coumerih, Bird City, Kansas
15:30 MDT – Goodland, KansasThe National Weather Service (NWS) in Goodland, Kansas
reported 90 mph winds at St. Francis, Kansas and gusts 65–85
mph at Goodland. Prior to this event, the area experienced a six
year drought (see table below) and the topsoil moisture in NW
Kansas was very low by the end of May. Afternoon temperatures
frequently topped 80 degrees during the month, and only two days
of significant rainfall were reported for the year, prior to May 29th.
17:15 MDT – Grinnell, KansasThe poor visibility caused the Kansas Highway Patrol to close I-70 West of Wakeeney
for about two hours. However, because of the fast moving nature of the storm, at
least 10 vehicle accidents occurred with two resulting in the deaths of two individuals
including Kansas State Senator Stan Clark. NWS reports winds of 69 MPH.
16:00 MDT – Colby, KansasRobert Grace took a series of photos flying near Colby, Kansas. NWS reports winds of
67 mph and “metal roofs ripped from buildings and several power poles were broken”.
Sherman Co. (Goodland) precipitation and departure from normal
Year: 2000 2001 2002 2003 2004 Normal
millimeters: 427 466 280 373 566 504
departure: -77 -38 -224 -131 62
Weather Total Suspension Total Suspension
Continuous Winter Wheat Dryland Simulated 0.1 (0.3) 0.05 (0.2) 0.0 0.0Continuous Winter Wheat Irrigated Measured 0.2 (1.0) 0.1 (0.7) 0.0 0.0Continuous Winter Wheat Dryland Measured 29.0 (129.1) 22.7 (101.3) 0.0 0.0Winter Wheat - Fallow Dryland Simulated 4.3 (19.2) 3.0 (13.2) 0.0 0.0Winter Wheat - Fallow Dryland Measured 38.1 (169.8) 29.1 (129.9) 0.0 0.0Continuous Grain Sorghum Dryland Simulated 9.3 (41.2) 6.3 (28.0) 0.0 0.0Continuous Grain Sorghum Irrigated Measured 0.9 (3.9) 0.5 (2.4) 0.0 0.0Continuous Grain Sorghum Dryland Measured 15.0 (67.0) 10.2 (45.6) 5.7 (25.5) 3.1 (14.0)Continuous Corn Dryland Simulated 3.3 (14.6) 2.0 (8.9) 0.0 0.0Continuous Corn Irrigated Measured 0.1 (0.4) 0.1 (0.3) 0.0 0.0Continuous Corn Dryland Measured 20.9 (92.9) 15.3 (68.2) 7.1 (31.5) 3.7 (16.4)
Rotation
kg/m2 (Tons/Acre)
The study of this storm will help in our understanding of such events including
management systems that control soil loss by wind under these conditions. This
study also provides experience using WEPS with measured weather - essential
to developing a WEPS based dust event warning system for highway,
agricultural, and environmental agencies.